WO2014024644A1

WO2014024644A1 - Signal processing device and signal processing method in wind profiler

Info

Publication number: WO2014024644A1
Application number: PCT/JP2013/069274
Authority: WO
Inventors: 松田　知也; 大治原田; 敬央山本
Original assignee: 三菱電機株式会社
Priority date: 2012-08-09
Filing date: 2013-07-16
Publication date: 2014-02-13
Also published as: EP2884300B1; US20150226849A1; EP2884300A4; EP2884300A1; US10234556B2; JP2014035276A; JP6150474B2

Abstract

The objective of the present invention is, in a wind profiler, to expand the number of acquired ranges until an altitude in which noise is mixed in a received signal even if noise is mixed accompanying transmission/reception changeover. The present invention is a signal processing device (103) in a wind profiler which emits a pulsed electromagnetic wave in a space, subsequently switches from transmission to reception, receives a reflected electromagnetic wave from an observation object, and measures wind velocity on the basis of the Doppler frequency of the received electromagnetic wave. The device is provided with an unnecessary data assessment unit (10) which detects a noise period in which switching noise occurs as a result of switching of the transmission and the reception, and an unnecessary data deletion unit (3) which converts the signal received in the noise period into substantially invalid data.

Description

Signal processing apparatus and signal processing method in wind profiler

The present invention relates to a signal processing device and a signal processing method in a wind profiler that measures a wind speed distribution in the sky.

In recent years, a technology for measuring the wind direction and speed of the sky with an atmospheric radar called a wind profiler is being established. The wind profiler can measure the wind direction and speed over the air every minute to several minutes. The wind information of the sky measured with such a high temporal resolution is effective for improving the accuracy of weather forecasts.

Regarding a wind profiler, for example, Patent Document 1 discloses a technique for improving the calculation accuracy of a wind speed vector. The wind profiler of Patent Document 1 calculates the Doppler velocity for each beam and altitude from the complex received signal, and confirms the consistency between the beams of the Doppler velocity for each altitude. Then, a beam combination for each altitude for calculating the wind speed vector is selected based on the consistency between the beams, and the wind speed vector is calculated for each altitude based on the selected beam combination for each altitude and the Doppler velocity.

Patent Document 2 discloses a signal processing technique for a wind profiler that improves the data acquisition rate in a wide altitude range. In the signal processing apparatus of Patent Document 2, an optimal incoherent integration time is set for each altitude. Then, a power spectrum is calculated from the Fourier-transformed data, and is time-integrated for a set incoherent integration time. Further, the low-quality Doppler velocity data is removed from the Doppler velocity calculated from the power spectrum obtained by incoherent integration, and the time average is performed.

JP 2001-159636 A JP 2002-168948 A

A type of weather radar that calculates accurate Doppler velocity when switching noise generated at the time of switching between transmission and reception is mixed in the data at the stage of pulse compression processing in a wind profiler that calculates the wind direction and speed from the ground to the sky. There is a problem that you can not.

In the prior art, in order to process only data within a range not affected by switching noise, the number of data acquisition ranges is reduced to avoid the effect of noise. However, in this case, the range of processing data that can be acquired is smaller than the observable range.

The present invention has been made to solve the above-described problems, and even in the case where noise associated with transmission / reception switching is mixed in the window profiler, the acquisition range up to an altitude at which noise is mixed in the received signal is obtained. The purpose is to increase the number.

In order to achieve the above object, a signal processing apparatus according to an aspect of the present invention radiates a pulsed electromagnetic wave into a space, switches transmission and reception, receives an electromagnetic wave reflected from an observation object, and receives the received electromagnetic wave. A signal processing apparatus for a wind profiler that measures wind speed from a Doppler frequency, and that detects a noise section in which switching noise is generated by switching between transmission and reception, and converts a received signal in the noise section into substantially invalid data. A signal suppression unit.

According to the present invention, the number of acquisition ranges can be expanded up to an altitude at which noise is mixed in the received signal by converting the received signal in the noise section where the switching noise is generated into substantially invalid data.

It is a block diagram which shows the whole structure of the wind profiler which concerns on embodiment of this invention. It is a block diagram explaining the principle of the signal processing apparatus of a wind profiler. It is a figure for demonstrating the principle of the pulse compression in a wind profiler. It is a figure for demonstrating the influence of the switching noise when it switches from reception to transmission in pulse compression. It is a figure for demonstrating the influence of the switching noise when it switches from transmission to reception in pulse compression. It is a figure which shows the example of the noise by the influence of transmission / reception switching of the maximum observation layer vicinity. It is a block diagram which shows the structural example of the signal processing apparatus which concerns on Embodiment 1 of this invention. 3 is a block diagram illustrating configurations of an unnecessary data determination unit and an unnecessary data deletion unit according to Embodiment 1. FIG. 6 is a diagram illustrating an example of a power spectrum for unnecessary data determination according to Embodiment 1. FIG. 6 is a diagram illustrating an example of a power spectrum for unnecessary data determination according to Embodiment 1. FIG. FIG. 6 is a timing diagram illustrating an operation of determining and deleting unnecessary data according to the first embodiment. 6 is a diagram for explaining that the influence of noise can be avoided by noise section determination / replacement according to Embodiment 1. FIG. It is a figure which shows the example of the power spectrum before removing the DC component which concerns on Embodiment 1. FIG. It is a figure which shows the example of the power spectrum after removing the DC component which concerns on Embodiment 1. FIG. 6 is a flowchart illustrating an example of a noise section determination / replacement operation according to the first embodiment. It is a block diagram which shows the structural example of the transmission / reception switching and frequency conversion part which concerns on Embodiment 2 of this invention. FIG. 10 is a timing diagram illustrating an example of attenuating switching noise according to the second embodiment.

FIG. 1 is a block diagram showing the overall configuration of a wind profiler according to an embodiment of the present invention. The wind profiler 100 is a type of Doppler radar, and includes an antenna device 101, a transmission / reception device 102, a signal processing device 103, a wind speed vector calculation device 104, and a display / recording device 105, as shown in FIG. In the wind profiler 100 configured as described above, a reflected wave of an electromagnetic wave radiated from the antenna device 101 into the air is received by the antenna device 101, and the received electromagnetic wave is amplified and frequency-converted by the transmission / reception device 102 and received. Converted to an IF (intermediate frequency) signal. The IF signal is subjected to analog-to-digital (A / D) conversion and frequency analysis processing by the signal processing device 103 to calculate spectrum data and send it to the wind speed vector calculation device 104. The wind speed vector calculation device 104 calculates the Doppler speed from the spectrum data, and then calculates the wind speed vector. The calculated wind speed vector is displayed or recorded by the display / recording device 105.

FIG. 2 is a block diagram for explaining the principle of the signal processing device of the wind profiler. The signal processing device 103 includes, for example, an A / D conversion unit 1, a phase detection unit 2, a CIC decimation unit 4, an FIR unit 5, a pulse compression unit 6, a coherent integration unit 7, an FFT processing unit 8, and an incoherent integration unit 9. Composed. Hereinafter, the conceptual operation of the signal processing apparatus will be described.

The reception IF signal output from the transmission / reception device 102 in FIG. 1 is input to the AD conversion unit 1. The AD converter 1 converts the received IF signal from an analog signal to a digital signal. This digital signal is input to the phase detection unit 2 and phase-detected by complex multiplication of a sine / cosine signal to generate an I / Q signal. The I / Q signal is input to the CIC decimation unit 4 and thinned out by a CIC filter (CascadesIntegration Comb Filter). The thinned I / Q data is input to the FIR unit 5 to correct the amplitude characteristic of the I / Q data after CIC filtering.

The pulse compression unit 6 performs pulse compression demodulation on the I / Q data after amplitude characteristic correction. The demodulated I / Q data is coherently integrated by the coherent integrator 7, Fourier-transformed by the FFT processor 8, and input to the incoherent integrator 9. The incoherent integration unit 9 calculates the power spectrum obtained by obtaining the power value from the Fourier transform of the received signal data, and then integrates the power spectra obtained at a plurality of times (incoherent integration). After integration) Output as power spectrum.

Here, the principle of pulse compression in the wind profiler will be described. FIG. 3 is a diagram for explaining the principle of pulse compression in the wind profiler. FIG. 3 shows the principle of 4-bit pulse compression using the Spano code. FIG. 3 shows a case where the signal reflected by the R4 layer is decoded (demodulation of pulse compression). “1” and “−1” in the transmission represent signals having phases of 0 and π, respectively. By multiplying the received signal at the timing at which the transmission pulse is reflected and received by the R4 layer by the transmitted bit pattern and adding it in the time direction, only the data reflected by the R4 layer is the number of bits (in FIG. Min) pile up. When this is integrated for a plurality of coherent pulses transmitted with different bit patterns, the reflected signal from the R4 layer is multiplied by a plurality, and the others are canceled out. In the example of FIG. 3, it is possible to obtain 8 times the reception intensity due to the effect of 4 bit pulse compression × 2 coherent integration. Then, the reflected signals from other layers are canceled out to zero.

In principle, even before and after the transmission / reception switching, a part of the signal necessary for the decoding is already received before the transmission / reception switching. However, since noise accompanying transmission / reception switching is mixed in the data to be decoded, the noise appears in the spectrum data, and a Doppler velocity different from the actual echo is calculated.

FIG. 4 is a diagram for explaining the influence of switching noise when switching from reception to transmission in pulse compression. FIG. 5 is a diagram for explaining the influence of switching noise when switching from transmission to reception in pulse compression. In the example of FIG. 4, switching from reception to transmission is performed immediately after the last bit of the transmission signal is reflected by the R4 layer and received. Therefore, noise is mixed in the received signal reflected from the layer above the R4 layer. In the example of FIG. 5, the transmission is switched from reception to reception shortly before the first bit of the transmission signal is reflected by the R6 layer and received. Therefore, noise is mixed in the received signal reflected from the layer below the R6 layer. FIG. 6 is a diagram illustrating an example of noise due to the influence of transmission / reception switching near the maximum observation layer.

∙ In order to avoid the influence of noise, if the number of ranges to be acquired is limited so that only the unaffected range is processed by excluding the reflected wave from the layer in which noise is mixed in the received signal, the observable range is narrowed. For example, in FIG. 4, the observable range is narrowed below the R4 layer. In the example of FIG. 5, the observable range is limited to an altitude of the R6 layer or higher. In the spectrum of FIG. 6, it is impossible to observe an altitude of 10 km or more.

Embodiment 1 FIG.
FIG. 7 is a block diagram showing a configuration example of the signal processing apparatus according to Embodiment 1 of the present invention. The signal processing device 103 shown in FIG. 7 corresponds to the signal processing device 103 of the window profiler 100 shown in FIG. The signal processing apparatus 103 according to the first embodiment includes an unnecessary data deletion unit 3, an unnecessary data determination unit 10, and a DC component removal unit 15 in addition to the basic configuration shown in FIG.

Unnecessary data determination unit 10 determines the presence or absence of noise mixed during transmission / reception switching with respect to the power spectrum output from incoherent integration unit 9, and detects a noise interval. The unnecessary data determination unit 10 sets a replacement section that should be substantially invalidated (unnecessary data should be deleted) in the received signal in accordance with the noise section. The unnecessary data determination unit 10 sends a signal indicating the replacement section to the unnecessary data deletion unit 3. The unnecessary data deleting unit 3 substantially invalidates the data in the replacement section with respect to the I / Q data output from the phase detection unit 2 in accordance with the signal indicating the replacement section. That is, the data in the replacement section is replaced with a certain value, for example, “0”. The DC component removal unit 15 removes a DC component that appears prominently by deleting unnecessary data from the power spectrum output from the incoherent integration unit 9. Hereinafter, detailed processing operations of the unnecessary data deleting unit 3 and the unnecessary data determining unit 10 will be described.

FIG. 8 is a block diagram illustrating the configuration of the unnecessary data determination unit and the unnecessary data deletion unit according to the first embodiment. The unnecessary data determination unit 10 includes a maximum value calculation unit 11, a short distance determination unit 12, and a long distance determination unit 13. The unnecessary data deletion unit 3 includes a replacement gate signal generation unit 31 and a replacement processing unit 32.

The maximum value calculation unit 11 of the unnecessary data determination unit 10 calculates a maximum value for each altitude (distance from the wind profiler 100) for the power spectrum input from the incoherent integration unit 9. The maximum value calculation unit 11 outputs the calculated maximum value to the short distance determination unit 12 and the long distance determination unit 13.

The short distance determination unit 12 is a noise section of the received signal reflected by a layer near the wind profiler 100, that is, a range in which the received signal should be substantially invalidated due to noise generated by switching from transmission to reception (replacement section). Is detected. The long distance determination unit 13 is a noise section of the received signal reflected by a layer far from the wind profiler 100, that is, a range in which the received signal should be substantially invalidated due to noise generated by switching from reception to transmission (replacement section). Is detected.

Although not shown in FIGS. 7 and 8, a signal for switching between transmission and reception is input from the transmission / reception device 102 to the signal processing device 103. Alternatively, the signal processing device 103 generates transmission / reception switching and instructs the transmission / reception device 102. In any case, the transmission / reception switching timing is known by the unnecessary data determination unit 10.

The short distance determination unit 12 sets a replacement section for a reception signal reflected by a near layer where noise is generated due to switching from transmission to reception. The short-range determination unit 12 performs replacement from the transmission period to the reception period (to the later time) until the maximum value of the power spectrum (in the near layer) is equal to or less than the threshold value based on the switching timing from transmission to reception. Extend the section. For example, when the maximum value of the power spectrum exceeds the threshold, the replacement interval is extended by a certain step time, and the change of the maximum value of the power spectrum is observed. This operation is repeated until the maximum value is less than or equal to the threshold value.

The long distance determination unit 13 sets a replacement section for a received signal reflected by a far layer where noise is generated due to switching from reception to transmission. The long distance determination unit 13 uses the timing of switching from reception to transmission as a reference until the maximum value of the power spectrum (in the far layer) is equal to or less than the threshold value, from the subsequent transmission section to the previous reception section (front Extend the replacement interval. For example, when the maximum value of the power spectrum exceeds the threshold, the replacement interval is extended before a certain step time, and the change in the maximum value of the power spectrum is observed. This operation is repeated until the maximum value is less than or equal to the threshold value.

Since the altitude affected by the noise on the near side and the altitude affected by the noise on the far side are known by the transmission / reception switching timing (see FIGS. 4 and 5), the range of the altitude to be determined can be determined. it can. The short distance determination unit 12 and the long distance determination unit 13 may set a noise section in the range of each altitude. Further, the short distance determination unit 12 determines the end point of the replacement section in a time range (determination range) after the switching timing from transmission to reception. Then, the long distance determination unit 13 determines the start point of the replacement section in the previous time range (determination range) from the switching timing from reception to transmission.

FIG. 9A and FIG. 9B are diagrams showing examples of the power spectrum for unnecessary data determination according to the first embodiment. 9A and 9B represent the power spectrum of the received signal reflected at a certain altitude. FIG. 9A shows the case where the maximum value exceeds the threshold value, and FIG. 9B shows the case where the maximum value is less than the threshold value. Each of the short distance determination unit 12 and the long distance determination unit 13 extends the replacement section until the maximum value of the power spectrum of the target altitude is equal to or less than the threshold value.

The short distance determination unit 12 and the long distance determination unit 13 replace the received signal data with a constant value as a noise interval based on information on the maximum value of the power spectrum, the determination threshold, the determination range, and the step time. A position where I / Q data is replaced with a constant value is calculated, and a replacement signal (a short distance replacement signal and a long distance replacement signal) is output. Here, the short-distance determination unit 12 and the long-distance determination unit 13 have the same processing flow except that the set threshold value, determination range, and step time (for short-distance and long-distance) are different. If the direction to the later time is positive and the step time is a positive value for short distance and a negative value for long distance, the same algorithm can be used for short distance and long distance.

FIG. 10 is a timing chart showing an operation of determining and deleting unnecessary data according to the first embodiment. The transmission / reception switching signal indicates transmission at a low level and reception at a high level. The transmission type signal appears in the transmission interval. The reference trigger indicates a switching timing from transmission to reception, and is a reference for setting a noise section (replacement section). The short distance determination unit 12 extends the replacement section backward (in the direction in which time advances) from the reference trigger. The long distance determination unit 13 extends the replacement section forward (in the direction of going back in time) from the reference trigger. FIG. 10 shows a state in which the replacement interval is extended in the order of the time interval by determining the presence or absence of noise in one time interval and setting the replacement interval in the subsequent time interval.

The replacement gate signal generation unit 31 in FIG. 8 generates a replacement gate signal from the short distance replacement signal and the long distance replacement signal input from the short distance determination unit 12 and the long distance determination unit 13. The replacement gate signal is a replacement section from a long distance replacement signal to a subsequent short distance replacement signal. In FIG. 10, the low level of the replacement gate signal indicates the replacement interval.

In the replacement processing unit 32, the I / Q data input from the phase detection unit 2 is set to a constant value, for example, data “0”, only at the portion that is gated according to the replacement gate signal input from the replacement gate signal generation unit 31. Replace with The data to be replaced is not limited to “0” and may be a constant value. FIG. 10 shows how the received signal data in the replacement interval in the time interval after the time interval in which the presence / absence of noise is determined is replaced with “0” (a constant value), and the replacement interval is expanded in the order of the time interval. ing.

FIG. 11 is a diagram for explaining that the influence of noise can be avoided by the noise section determination / replacement according to the first embodiment. The left side of FIG. 11 is the same as FIG. “1” and “−1” represent signals having phases of 0 and π, respectively. “0” represents a constant value whose phase is not π / 2 (or −π / 2) and whose amplitude is 0. By replacing a signal affected by noise represented by “X” with a constant value “0”, for example, noise is not included in the data after pulse compression of the R6 layer, so the Doppler speed of the R6 layer Can be calculated correctly. By replacing the data mixed with noise at the time of transmission / reception switching with 0, only the atmospheric echo appears in the demodulated spectrum data as shown in FIG.

The layer in which the data is replaced, for example, the R6 layer is less accurate because the number of compressed and stacked layers is smaller than the R4 layer in which the data is not replaced, but it can be compensated by increasing the incoherent integration time. it can. In a high altitude layer, the time change of the wind speed is small and the time resolution may be small, so that it is sufficiently practical.

By performing the above replacement process, the DC component is mixed into the spectrum data due to the discontinuity of the boundary between the actual data and the replacement data. Therefore, the DC component (point of Doppler 0) is deleted by the DC component removing unit 15 in FIG. For example, the DC component is removed by interpolating from data adjacent to the DC component of the power spectrum. This eliminates the problem caused by data discontinuity.

FIG. 12A is a diagram showing a power spectrum before the DC component according to Embodiment 1 is removed. FIG. 12B is a diagram showing a power spectrum after the DC component according to Embodiment 1 is removed.

FIG. 13 is a flowchart showing an example of the noise section determination / replacement operation according to the first embodiment. As described above, by allowing the noise interval determination threshold, determination range, and step time to be set individually on the short distance side (timing when switching from transmission to reception) and the long distance side (timing when switching from reception to transmission) The determination process can be realized by the same method.

Unnecessary data determination unit 10 first reads the power spectrum from incoherent integration unit 9 (step ST1). The unnecessary data determination unit 10 moves (sets the determination altitude) to the power spectrum of the first altitude in the determination range in the input power spectrum (step ST2). Next, the maximum value calculation unit 11 calculates the maximum value of the power spectrum of the moved altitude (step ST3).

The short distance determination unit 12 or the long distance determination unit 13 compares the maximum value with the threshold value, and if the maximum value ≦ the threshold value (step ST4; YES), the replacement signal delay step ST5, and if the maximum value> the threshold value (step) ST4; NO), the process proceeds to an end altitude determination step ST7. As described above, whether it is a short distance or a long distance is selected based on the altitude to be determined. For example, when the altitude is below a certain altitude, the short distance determination unit 12 determines, and when the altitude is higher than that, the long distance determination unit 13 determines. The threshold for determining the maximum value, the time step to be extended, and the reference timing (reference of the short distance side replacement signal and the long distance side replacement signal) are changed depending on whether the distance is short distance or long distance.

In replacement signal delay step ST5, the output timing of the replacement signal is extended by the step time set based on the previous replacement signal, and the process proceeds to time update step ST6. As described above, the step time takes a positive value for short distance and a negative value for long distance, with the direction to the later time being positive. The short distance determination unit 12 extends the short distance side replacement signal in the direction of delaying, and the long distance determination unit 13 extends the long distance side replacement signal in the direction of advancing. In the time update step ST6, the time interval to be processed (one transmission interval and the subsequent reception interval) is advanced to the next time interval, the altitude to be processed is initialized, and the processing returns to the data reading step ST1. .

On the other hand, if the maximum value is greater than the threshold (step ST4; NO), it is determined in the end altitude determination step ST7 whether the altitude in the threshold determination step has reached the end altitude (ST7). As a result of the determination, if the end altitude has been reached (step ST7; YES), the process ends. If the end altitude has not been reached (step ST7; NO), the process proceeds to altitude update step ST8. In altitude update step ST8, the altitude to be processed is updated to the next altitude, and the process is repeated from the maximum value calculation of the altitude power spectrum (step ST3).

As a result of the noise section determination / replacement processing performed by the unnecessary data determination unit 10 and the unnecessary data deletion unit 3, the DC component mixed in the power spectrum due to the discontinuity of the boundary between the actual data and the replacement is obtained by the DC component removal unit 15. Removed.

As described above, according to the signal processing apparatus 103 according to the first embodiment, the demodulated power can be obtained by replacing the data mixed with noise at the time of transmission / reception switching with a constant value and removing the DC component. Only atmospheric echoes will appear in the spectrum. As a result, the number of data acquisition ranges can be expanded to an altitude at which noise is mixed in the received signal.

Embodiment 2. FIG.
FIG. 14 is a block diagram illustrating a configuration example of a transmission / reception switching / frequency converting unit according to Embodiment 2 of the present invention. In the second embodiment, a received signal including switching noise is attenuated to an intensity (substantially invalid level) that is not affected at the stage of the analog signal.

The transmission / reception switching / frequency conversion unit 112 includes a transmission / reception switching unit 20, an attenuation unit 21, a mixer 22, a 2 distribution unit 23, a STALO (stable local oscillator) 24, and a mixer 25. The transmission / reception switching / frequency conversion unit 112 in FIG. 14 is included in the transmission / reception device 102 in FIG. 1, but here, at least the attenuation unit 21 is handled as a part of the signal processing device 103.

The periodic signal having a constant frequency generated by the STALO 24 is supplied to the mixer 25 on the transmission side and the mixer 22 on the reception side by the two distribution unit 23. The transmission IF signal is up-converted to a carrier frequency by the mixer 25 and sent to the transmission / reception switching unit 20 as a transmission RF signal. The transmission / reception switching unit 20 switches between transmission and reception in order to transmit the transmission RF signal to the transmission unit and the reception RF signal to the reception unit. In the case of transmission, the transmission RF signal from the mixer 25 is sent to the antenna apparatus 101. In the case of reception, the reception RF signal from the antenna device 101 is sent to the attenuation unit 21.

The attenuating unit 21 attenuates the signal only in the portion of the attenuated gate signal with respect to the received RF signal input from the transmission / reception switching unit 20. The attenuation gate signal is supplied from the signal processing device 103.

In the signal processing device 103, for example, a timing signal (transmission / reception switching signal shown in FIG. 10) for switching between transmission and reception is acquired, and a time range of a predetermined length from the timing signal, which is a range where noise measured in advance is generated. Generated as an attenuated gate signal. Alternatively, the replacement signal of the first embodiment is supplied as an attenuation gate signal by adjusting the delay time from the attenuation unit 21 to the unnecessary data determination unit 10.

The received RF signal with the attenuated gate signal portion attenuated is converted to an intermediate frequency by the mixer 22 and sent to the AD converter 1 of the signal processing device 103 as a received IF signal. The portion of the attenuated gate signal in which switching noise for transmission / reception switching is mixed is attenuated to a substantially invalid level, so that an unnecessary peak does not appear in the power spectrum.

FIG. 15 is a timing diagram showing an example of attenuating switching noise according to the second embodiment. Strong switching noise is mixed in the received signal at the rise and fall of the transmission / reception switching signal. By attenuating only the signal in the section where the switching noise is mixed, the switching noise is attenuated and the actual echo can be made unaffected.

The present invention is capable of various embodiments and modifications without departing from the broad spirit and scope of the present invention. The above-described embodiments are for explaining the present invention and do not limit the scope of the present invention. The scope of the present invention is shown not by the embodiments but by the claims. Various modifications within the scope of the claims and within the scope of the equivalent invention are considered to be within the scope of the present invention.

This application claims priority based on Japanese Patent Application No. 2012-176756 filed on August 9, 2012, including the specification, claims, figures, and abstract. The disclosure of Japanese Patent Application No. 2012-176756 is included in this application as a whole by reference.

1 AD conversion unit, 2 phase detection unit, 3 unnecessary data deletion unit, 4 CIC decimation unit, 5 FIR unit, 6 pulse compression unit, 7 coherent integration unit, 8 FFT processing unit, 9 incoherent integration unit, 10 unnecessary Data determination unit, 11 maximum value calculation unit, 12 short distance determination unit, 13 long distance determination unit, 15 DC component removal unit, 20 transmission / reception switching unit, 21 attenuation unit, 22 mixer, 23 2 distribution unit, 24 STALO, 25 mixer , 31 replacement gate signal generation unit, 32 replacement processing unit, 100 window profiler, 101 antenna device, 102 transmission / reception device, 103 signal processing device, 104 wind speed vector calculation device, 105 display / recording device, 112 transmission / reception switching / frequency conversion unit.

Claims

A signal processing device in a wind profiler that radiates a pulsed electromagnetic wave in space, switches between transmission and reception, receives an electromagnetic wave reflected from an observation object, and measures the wind speed from the Doppler frequency of the received electromagnetic wave,
A detection unit for detecting a noise section in which switching noise is generated by switching between transmission and reception;
A signal suppression unit that converts the received signal in the noise section into substantially invalid data;
A signal processing apparatus comprising:
A Fourier transform processing unit for performing Fourier transform on the data of the received signal;
An incoherent integrator that calculates the power spectrum from the data of the received signal Fourier-transformed by the Fourier transform processing unit, and time-integrates the power spectrum obtained at a plurality of times for an incoherent integration time;
With
The detection unit detects the noise interval by determining the presence or absence of a noise signal from the power spectrum after the incoherent integration, and sets a replacement interval for replacing the received signal with a constant value,
The signal suppression unit is
Based on the replacement interval set by the detection unit, an unnecessary data deletion unit that replaces the data of the received signal in the replacement interval with a constant value;
A DC component removing unit that removes a DC component of the power spectrum generated by replacing the data of the received signal with the constant value in the unnecessary data deleting unit;
including,
The signal processing apparatus according to claim 1.
The detection unit determines the presence or absence of noise in one time interval, sets the replacement interval in a subsequent time interval,
The signal suppression unit replaces the data of the reception signal in the replacement interval in the time interval after the time interval in which the detection unit determines the presence or absence of noise with the constant value.
The signal processing apparatus according to claim 2.
The detection unit calculates the maximum value of the power spectrum after the incoherent integration, and according to a result of comparing the maximum value and a threshold value within a set determination range, the predetermined step time as a unit. The signal processing apparatus according to claim 2 or 3, wherein a replacement section is set.
The detector is
Within the determination range of the timing at which the window profiler switches from transmission to reception, when the maximum value is larger than the first threshold, the replacement interval of the timing at which the window profiler switches from reception to the first step time is set. Extend to time,
When the maximum value is larger than a second threshold within the determination range of the timing at which the window profiler switches from reception to transmission, the replacement interval of the timing at which the window profiler switches from reception to transmission is set to the second step time before. Extend to time,
The signal processing apparatus according to claim 4.
The detection unit generates a replacement gate signal indicating the start and end of the replacement section,
The signal suppression unit replaces the received signal data in the section specified by the replacement gate signal with the constant value.
The signal processing apparatus according to claim 2.
The signal processing apparatus according to any one of claims 2 to 6, wherein the signal suppressing unit removes the DC component by interpolating from data adjacent to the DC component of the power spectrum.
The detection unit captures a timing signal for switching between transmission and reception, detects a predetermined length of time from the timing signal as the noise interval,
The signal suppression unit attenuates the received signal in the noise interval;
The signal processing apparatus according to claim 1.
It is a signal processing method performed by a wind profiler that radiates pulsed electromagnetic waves in space and then switches between transmission and reception, receives electromagnetic waves reflected from the observation object, and measures the wind speed from the Doppler frequency of the received electromagnetic waves,
A detection step of detecting a noise section in which switching noise is generated by switching between transmission and reception;
A signal suppression step of converting the received signal in the noise interval into substantially invalid data;
A signal processing method comprising:
Fourier transform processing step for performing Fourier transform on the received signal data;
An incoherent integration step of calculating a power spectrum from the data of the received signal Fourier-transformed in the Fourier transform processing step, and time integrating the power spectrum obtained at a plurality of times for an incoherent integration time;
With
In the detection step, the noise interval is detected by determining the presence or absence of a noise signal from the power spectrum after the incoherent integration, and a replacement interval for replacing the received signal with a constant value is set.
The signal suppression step includes
Based on the replacement interval set in the detection step, unnecessary data deletion step of replacing the data of the received signal in the replacement interval with a constant value;
A DC component removing step for removing a DC component of the power spectrum generated by replacing the data of the received signal with the constant value in the unnecessary data deleting step;
including,
The signal processing method according to claim 9.
In the detection step, a timing signal for switching between transmission and reception is captured, and a predetermined length of time is detected as the noise interval from the timing signal,
In the signal suppression step, the received signal in the noise section is attenuated.
The signal processing method according to claim 9.